Exhaust gas recirculation valves serve to control exhaust gas recirculation in internal combustion engines in the interest of reducing pollutants in the exhaust gas. External exhaust gas recirculation valves are not arranged in the internal combustion engine block, but outside the engine block. They therefore generally do not have an active cooling, so that all components of the exhaust gas recirculation valve are subjected to high thermal stresses. The essential functional parts of an external exhaust gas recirculation valve are constituted by an electric drive motor, a reduction gearing, and a valve body. The gearing may be any gearing that is as compact as possible, for example, a planetary gearing, a worm wheel gearing, etc.
For reasons of costs, a mechanically commutated DC drive motor is used as the drive motor for exhaust gas recirculation valves. A drawback of mechanical commutation is the relatively strong electromagnetic interference generated in the process. Reactance coils and capacitors are generally used to suppress the interference in a mechanically commutated motor, which are mounted as close to the rotor as possible to achieve the best suppression effect possible. However, capacitors can only tolerate temperatures of 150° C., so that they cannot readily be used for suppression in exhaust gas recirculation valves of the common type, since, in addition, also the motor rotor is heated to temperatures far above 200° C. in operation.